Form grinding machine



Sept. 14, 1943. F. A. WARD FORM GRINDING MACHINE 5 Sheets-Sheet 1 Filed Jan. 6, 1941 INVENTOR.

8% FREDERICK A.WARD

ATTORNEYS Sept. 14; 1943. WARD- FORM GRINDING MACITIINE Filed Jan. 6, 1941' 5 Sheets-Sheet 2 NQE INVENTOR.

BY FREDERICK A.WARD 4 ATTORNEYS INVENTOR.

5 Sheets-Sheet 3 Sept. 14, 1943. F. A. WARD FORM GRINDING MACHIN E Filed Jan. 6, 1941 FREDERlCK A.W'ARD ATTORNEYS w: m g n8 H I a w ,H C l /o Sept. 14, 1943. F, A A D 2,329,428

FORM GRINDING MACHINE Filed Jan. 6, 1941 5 Sheets-Shet 4 INVENTOR. FREDERICK A.WARD

ATTORNEYS 5 Sheet s-Sheet 5 INVENTOR.

ATTORNEYS F. A. WARD FORM GRINDING MACHINE Filed Jan. '6 1941 FREDERICK AWARD WWLMMM Sept. 14, 1943.

Patented Sept 14, 1943 2,329,428, I FORM GRINDING MACHINE i Frederick A. ward, nigm nara k, Mich assignor-to The GearfGrinding Machine Company, "jf llamtrarnck, Mich., a corporation of Michigan Application January 6, 1941,;Serial No, 373,352

Thefinvention' relates to grinding machines of that type-in which a formed grinder wheel'suc- *cessively operates on difie'rentportionsof' the work to repeat the pattern in the surface thereof. More particularly, the invention is designed for" use in the grinding" of gears applicableto many other uses. v Grinding]machines 'designed for the form grinding of gear teeth generally consist of a work support, a grinder wheel movably mounted in relation to the work to' perform the grindin operation thereon," a "trimming mechanism for but it is' also forming the grinder "-wheel; and an indexing mechanism through which the' teeth ofjthe gear are successively presented in operative'relation to the formed grinder wheel. Inasmuch as the teeth are' successively ground, the time required for the completion of the gear is proportional to its numberd'fteeth Thus with gears having a large number of teeth, a considerable interval of'time is required for the completion of the work. i

It is the object of the invention to expedite the completion of the gear' by the pr'ovision or a plurality of grinder wheels which simultaneously operate upon different portions of the work. This will "divide the time interval for the com- Dletion of the'work by the number of separate grinder'wheels thus employed. It is; however,

absolutely essential that the surfaces ground by the separate wheels-should exactly correspond in form and in indexed relation tof'each other. The invention, therefore; consists in the com Figure'lO is ajpl'a'n' view showing in full lines the" trimming mech'anlsmfoperatively arranged in relation to one of the grinder wheels and in dotted lines arranged in operative relation to the othergrinder wheel; 3 a

Figure 11 is a side elevation, partly in section,

. of the carrierframeand trimming mechanism mounted-thereon.

I v I Gen'eraliconstruct ion r My improvedgrinding machine comprises generally a suitable' base A on whichis centrally mounted a "rotatively adjustable Work holder B, a plurality of mountings and 0? for separate vertically movable 'grin der wheels" D and D, and an indexing mechanism E through which the work on the holderissuccessively :rotatively advanced in relation to the grinderwheels As specifically shown, there'is onlyEa', single pair of grinder wheels D andi D but it is obviousthat 'a larger number" may be-"used'ii desired. Where the gear tobe groundhas' an even number of teethfthe grinder wheels Band D may be positioned in the same plane (in cally'opposi'te sides of the work support; On the other hand, if ?the number o f;teeth*is odd, then the jplane'ofjoneofythe grinder wheels must be at an angle to ,thatfof the other wheel'corre spending to"one,- half of' the circular pitch? of the teeth. This necessitates means for adjusting one of the mountings, as for instance C, around the axis of the work hol der, the amount of such adjustment depending upon various struction'an'd organiz'ation 'of the grinding machine through hich 'such' result may be ob- 'tained. T

'Inthe'dr'awingsz' V "Figure 1" is asectional front elevation of my improved grinding machine; l

" Figure-2 is a plan view thereof; 1 1

Figure 3' is a diagrammatic front elevation illustrating the hydraulic operating connections and controlling means therefor;

Figure 4 is a diagrammatic plan view;' 4

Figure5 is an "enlarged end elevation showing the" indexing mechanism and its operating connections; A Figure 61s a plan view of Figure 5; v

Figur'e 'l' is a front elevation of a portion of Figure "5;" r l u Figure '8 is a sectionalfelevation showing the locking and controlling means for the indexing mechanism;

7 Figure 9 is an endelevation of soine- -ofthe elementsshowninFlgureS;

to the work.

factorssuch as'the diameter of the gear, the'cir- 'cular pitch{of'-the teeth, etc. "r amac mi is also provided with motors F and F for other driving'" means for rotating the grinder-wheels,

a feed mechanism such as, hydraulic rams G u and" G" for raising and lowering the grinder wheels in paths; crossing the 'work', actuating means for the'indexing mechanismsuch-as'a hydraulic motor. H, and means for timing, the

alternate operations of said'feeding mechanism 'andindexing operating mechanism. In addition :to these elements; there is a trimming a 'rnechanism I for" .iorming. the .grinder, wheels together with means through which this mechanism may be successivelyjarranged in operative relation to each wheel when saidgwheels are a in proper angular relation to each, other and The work, holder B is preferably Supported on'a circular grooved track B'ot V'-shaped cross Grinder wheel mountings Each of the grinder wheel mountings C and C comprises a column C having a slideway C thereon for a vertically movable carriage C and at the upper end of this carriage is a horizontally extending guideway C for a transverselymovable carriage C A bearing C" on the latter carriagej receives the arbor of the grinder wheel, said wheel being arranged in a plane passing through the 1 axis of the work holder. Thus the movement of the carriage C on the vertically extending slideway C will carry the grinder Wheel across the periphery ofthe work or gear wheel J. The carriage is actuated by the hydraulic ram G aswill be hereinafter set forth. i

I Angular adjustment for grinderwheel D As before statedywhere the gear to be ground has an even number of teeth, the grinder wheels D and D may be arranged in a common plane on diametrically opposite sides of the gear to properly register with the teeth thereof On theother hand, where the number of; teeth isodd, the plane of one of these grinder-Wheels must be angularly displaced from the-plane of the other wheel an amount equal to one-half the circular pitch of the teeth. To permit of. suchadjustment, the mounting forthe grinder Wheel D. is movably supported on .the base A but is held at a fixed radial distance from the axis of the work holder by an arm I; secured to the column (1 and provided at one endwith a bearing K engaging a pin K2, This pin is secured tothe base A in axial alignment with the work holder'and, therefore, permits angular adjustment of the columnand other elements of the. grinder-wheel mounting about this axis. As shown, the adjustment means comprises a bifurcated bracket K 01i the base, having: adjusting screws Kfin the furcations thereof for engaging opposite sides of a finger K secured ,to and projecting outwardly from the Indexing mechanism 2 g V I The rotative adjustment of the work holder to present suocessive teeth in proper registration to the grinder wheels is accomplished by an indexing mechanism including the worm wheelB and worm B The indexing mechanism may be of any suitable construction but preferably, as shown, comprises a casing E containing a gear train E connected at one end with a shaft E which through the mediumof an intermediate shaft E3 and beveled gear wheels E His connected to a shaft E on which the worm B is mounted. The jgear train E includes one or more change gearsand the opposite'endof the, train is connected to an external pinion H which is actuated by Jthe "hydraulic motor H. ,This motor comprises a cylinderH containing an elongated piston H having a rack H on one side thereof intermeshing with the pinion H which'la-tter extends through a slot H in the central portion of the cylinder H The piston is moved in opposite directions by thefluidwhich is alternately admitted to opposite ends of the cylinder. ,There is also a stop H preferably a screw threaded rod engaging one of the heads of the cylinder and adjustable therein to limit the stroke of the piston. The indexing'mechanism also includes a notched wheel or disc E which is engaged by a tapering locking dog E to hold said disc and connected gear train in an exactly predetermined position. The dog E is mounted on a rock arm E which is actuated by a spring E in a direction to withdraw the dog and is moved into locking position by a hydraulic motor E".

Operating mechanism Electric motors F and F have a driving conznectlon respectively to the arbors of the grinder wheels D and D which permits of the vertical movement of the carriages C As shown, this -driving connection comprises a foldable frame 1" carryingan intermediate pulley shaft F driven by a belt F from the motor and connected through abeit F with a pulley on the arbor of. the grinder wheel; The motors-F and F also'drive hydraulic pumps LandL" which'suppiy fluid under-pressure to the vfeeding mechanisms; A third. hydraulic pump L ldriven by a connection to one of the motors (not shown), supplies fluid under pressure to the controllingand timing mechanism forthe feed mechanism and indexing mechanism. The sequence of operations performed by the machine are: l.

First, to reciprocate theHca-rriages C on their slideways C therebyfiimultaneously moving the grinder wheels D and D aeross'thework to perform theirgrinding operations thereon;

Second, toreturn these carriagesto their originalposition; l

' Third, to stop or slow thctmovemcnt of said carriages while the grinder wheels are out ofcontact with the work and to; simultaneously operate the indexing mechanism: to rotatively adjust of the ram G while simultaneously the fluid from the lower end of the ram is exhausted through a conduit M also controlled by the valve M In the opposite position. of: the valve M the connections are reversed, pressure fluid passing through the conduit Mite the lower end of the ram and the exhaust fluid, escaping through the conduit M Similar connections, designated by the same reference lettersare arranged between the pump L and the ram G"; '"fillhcop rflt o 0f the reversing valves M is throughthe medium of a hydraulic reciprocatlngwmotor N which is supplied with fluid from the pump L and which, in turn, is controlled by a, reversing valve N. Fluid passes from the pump through a conduit N to the valve N and alternately to opposite ends of the cylinder. of theihydraulic motor Nvthrough conduits N andN, said conduits also alternately carrying the exhaust fluid under control of the valve N. The reciprocation of the motor N is communicated through a connecting rod W to rocker members N which reversethe valveslM The pump L also supplies. pressure zfluid through a conduit to'the hydraulic motor H which is under control of a reversing valve 0''. This valve.is operated by the hydraulic motor E through the medium of a mechanism ineluding a lever 0 directly connected to said motor E and which also actuates the rocker member E carrying the dog E The. leverv 0 is'connected by a link 0 with a rock arm 0 on' a shaft 0 The shaft extends longitudlnally'of and at the rear of the base A and isconnected through the medium of rock arms 0 links 0 and levers O with the valves M controlling the passage of fluid through the conduits M anew.

The shaft 0 is further provided with a'rock arm 7 0 connected through a linkO and bell crank lever O with the reversing valve 0,

From the arrangement above described; it will be understood that the operation of the rams G a! 11 G which raise and lower the grinder Wheels is controlled by the hydraulic motor N while' th'e hydraulic motor E controls the locking and un-,

grinding operations of both grinder'wheels D and D" will be completed and's'aid'wheels moved out of contact with the work before the indexing mechanism is unlocked and actuated'to rotate the work into a new position, the construction-being as follows. P is a bar mounted on the carriage C and extending parallel to the direction of move ment thereof. P and P are dogs adjustably secured to the bar P in spaced relation and'Pis an intermediate dog also adjustably secured to'said bar. ber 'Q mounted on a column Q rising from the base, said rocker member having two spaced nngers Q and Q one of which is actuatedby the dog P when the carriage C and bar P are moving in an upward direction, while the other finger is engaged by said dog when the said parts are moving in a downward direction The rock'- er member Q is connected by a link Q with a valve R which controls the flow of pressure fluid from the conduit 0 through a conduit R'to the hydraulic motor E Thus when the dog Pduring its'upward movement actuates the finger Q 'mitted to exhaust through the valve R." This permitsthe spring E to actuate the mechanism which unlocks the indexing gear train and operates the motor H. On the other'hand; whenthe dog P is moving downward and actuates the finger Q to rock the member Q in the reverse direction; pressure fluid is supplied through the conduit R to the motor E which locks the, gear train. This motor E also operating through the connecting mechanism opens the valves M to remove the restriction to flow of fluid through the conduits M and M It'further reverses .the 'valve'O' controlling the hydraulicmotonH so that the piston of the latter is returned'to-its original position. Such .returnflmovementzdoes The dog P cooperates with a rocker memnot, however, rotate the. gear. train E as there is'a'one-way clutchH" between the shaft of the piniomHf'rand theend'gear ofthe train. vThe.dogsP .zsa.nd'P ;.which are on opposite sides of-the dogiPt cooperate f'witha rocker member S which may; it desired, be coaxial with the rocker member 'Qbut independent thereof. Therocker member S is connected through the medium of a rocker arm S and connecting rod Swith a rocker arm S on a shaftS On this shaft S is a rock arm S which is connected to operate the reversing valveN controlling the operation of the motor N which, in .turn,yactuates the reversing valves M controlling the. reciprocation of the rams G'and G"; I

. Swichroniez'ng' means for the rams] v,

The rams Gland G] operate independently of each other to' respectively feed the grinder wheels D and -D-across the work. The speed; of -this feedingmovement isdepenclent: first, upon the pressure against the piston of theram; and second,-on the resistance of the work due to'athe amount ,of material which must be removed by the grinding. operation. Inasmuch as the resistancejoifered to the progress of the separate grinder wheels is notalways the same, it is obvious thatone of-the rams might complete its movement in one direction in advance ofwthe other 'ram., This,- if uncorrected, would throw the two'rams out'of step with each other-and with the indexingz mechanism. To avoid such result, I have 'provicledmeans'which, while still permitting the two rams to move independently, prevents the reversal of'direction or movement of either ram in advance of theother or before both have fully completed their downward strokes;theconstruction bein as follows.

v The reversing; valve N'is connected by a link T witha lever T which is'normally locked against movement by a latch. member T Adjacent to the levera'T' is-alever T which is connected by a link S with the rocker member S The two levers are-resiliently yieldably connected to each other by springpressed plungers 1 on the lever T bearing upon opposite sides of the lever T In the locked position of the lever T", the valve N I lS'POSitiOHCd'SO that the-reversing-valves M3 supply; pressure fluid to the upper ends of the rams, G and G. Consequently, whilethe-lever remains locked, therams can only move down-- ward and if the one completes its movement in advance of the other, it will remain stationary. The'operation of the dog P upon; th rocker member S and mechanism connected thereto will move the lever T andthrough the springpressed plunger T will exert-a pressure against the lever T. tending to movethelatter in a direction to reverse the valve- N. Such reversal cannot, however, take place until ,-the latch membert'l is operated to release the lever T. Suchrelease .of the latch "I 'is effected through the medium of anadjustable, cam dog U on the carriage C for grinder wheel D. whichjust before the completion of the downward stroke of the ram;Gf actuatesa mechanism connected to-said latch. This mechanism,-as shown, comprises a rock arm- U mounted on arockshaft U? and having a roller U in the path of the cam U. The rockshaft U carriesa' rockergarm' U with a roller U for con.- tacting with an elongatedrocker-member'U on a 'rockshaftflU The rockshaft U has a rock arm U connected bya rod U with a bell crank lever U connected with thelatch T2. The parts U; U U? andU are mounted ;on thesu-pportmg column for the grinder wheel -D' and are moved therewith about the axis of the'work holder during adjustment for positioning "said grinder wheel in relation to the work. The ele- Complete sequen e of operations Assuming that th work, such as a gear wheel to be ground, has been properly mounted on the work holder and proper adjustment has been made of said work holder and grinder wheels in relation to said gear, the operations are as follows: From their raised positions, the grinder wheels D and I)" are fed downward by th operatlon of the rams G and G which actuate'the carriages C. This downward feeding movement is controlled by the resistance of the work but the pressure of the grinder wheels against the work can never exceed that determined by the pressure of the hydraulic fluid. Assuming that the grinder wheel D performs its work faster than the grinder wheel D so that the ram G reaches the lower end of the movement in'advanc'e of the ram G, then the carriage for the grinder wheel D will remain stationary until the ram G has also completed its downward movement. This is for the reason that the latch member T remains in'locking engagement with the lever T although the dog P through the mechanism actuated thereby has tensioned the spring pressed plunger 'I. Just before the plunger G completes this downward movement, the cam U contacting with the roller U will, through the mechanism above described, releas the latch T permitting the lever T to be moved by the spring pressed plungers T so as to reverse the valve N. This will actuate the motor N to reverse the valves M thereby admitting pressure fluid to the lower ends of the rams G and G and actuating the same in an upward direction. After the grinder wheels have been elevated to a point which clears the work, the dog 1 contacting with the finger Q will rock the member Q to operate the valveR and thereby release the pressure fluid in the motor E. The spring E is then free to actuate the member E and locking dog E so as to free the disc ET and the gear train E. Simultaneo'usly the movement of the lever O and connecting mechanism will operate the valves M so as to restrict flow of fluid through the conduits M and M thereby slowing the further upward draulic motor H in a direction for actuating the gear train E through the medium of the rack H* and pinion H. The length of travel of the piston H has been determined by the adjustment of the stop H and is just sufficient to move the gear train E the required distance for indexing. While this operation is taking place, the continued slow upward movement of the rams will cause the dog P to actuate the rocker member S and through the connecting mechanism actuate the valves M reversing the same and starting the rams on their downward movement. This continues at slow speed until the dog P engages the finger Q rocking the member Q and actuating the valve R so as to restore fluid pressure on the motor E which moves the dog E into locking engagement with the disc E This move: ment will also through the connections described reverse the valve 0' so as to return the piston H to its original position. During this movement, the rack H engaging the pinion H will rotate the latter in the reverse direction but the one way clutch H will permit this movement withoutdisturbing the gear train E. The valves M will also be moved to their open position removing the restriction to the fiow of fluid through the conduits M and M This completes the cycle which is repeated without interruption.

In the progress of the work, the teeth' on one side of the gear wheel are successively ground by one of the grinder wheels and simultaneously the teeth on the other side of the gear wheel are successively groundby the other grinder wheel. When the tooth first ground by one or the grinder wheels comes in registration with the other grinder wheel, the latter is fed inward to take a second cut and this is repeated until the teeth are ground to their final form. It is thus apparent that the indexing of the wheel always progresses in one direction and the same teeth are alternately ground by the two grinder wheels. However, for the final finishing cycle, it may be desirable to withdraw one of the grinder wheels from operative relation to the work and to grind all of the teeth by a single wheel. This avoids any variation such as might be due to a minute inaccuracy in the setting of one grinder wheel in relation to the other.

To regulate the speed of travel of the rams G, I preferably provide valves M which variably restrict the supply of fluid from the pumps L and L to the valves M The valves M and M are preferably within the casings M located at the front of the machine. A lever M is connected to operate the valve M and a lever M is connected to operat the valve M in case for any reason it is desired to reverse it manually. However, normally the valves M are automatically operated.

For adjusting the grinder wheels toward the work the carriages C are moved on thewaysC through the operation of mechanisms not fully shown actuated by hand wheels C. There are also preferably micrometer gauges C which indicate the exact amount of movement of the grinder wheels toward or from the work.

Trimming mechanism The grinding wheels D and D must b trimmed to exactly the same cross sectional contour and this trimming must be repeated from time to time to restore the form. For this purpose, I employ a single trimming mechanism which may be successively placed in operative relation to each of the grinder wheels and in exact relation to indexed positions of the work. As specifically shown, this trimming mechanism is mounted on a carrier frame V which has a hinged or pivotal connection V' to the upper ends of a pair of posts W rising from the base in rear of the work holder. The frame V has a forwardly extending portion V and a rearwardly extending counterbalancing portion V Pivotally connected to the portion 4 V in axial alignment with the work holder is an In the trimming of grinder wheels for uselin' grinding gears, it is J customary toil fashion the cross sectional contour of the rg'rinder wheel 50 as to'correspond to the interdental space of thegear. There are',. therefore, separate: trimmer points for tlie'opposite sidesof the wheel which trace either exactly similar curves "orslightly modified curves according to thecontour desired. Where thecurves are not exactly the same, it is essential that in arranging the trimmer in operative relation to the respective grinder wheels, the trimmer points should be in the same relation in each position. In other words, the same trimmer should trim the side of each grinder wheel which forms the same side of the gear tooth. Such arrangement I obtain by swinging the extension member W about the pivot W from a position where the trimmers are in operative relation with one grinding wheel to the position where they are in operative relation to the other grinding wheel. If the two grinding wheels are in the same plane as is the case where the number of teeth in the gear is even, then this adjusting movement will be through an angle of 180. On the other hand, if the grinding wheels are not in the same plane as where the number of gear teeth is odd, then the angle of adjustment is less than 180 by an amount equal to one-half the circular pitch of the tooth to be ground. It is, of course,

essential that these two positions should be very exact in their registration with indexed positions of the work as otherwise the teeth ground by one of the grinder wheels would not properly index with those ground by the other wheel.

To accomplish th result just described, the member W extends radially outward from the axis of the pivot W a distance at least equal to the radius of the maximum size of gear wheel to be ground. This permits of adjusting the casing W and the trimmer points into operative relation to the grinder wheels when the latter are adjusted for grinding gear wheels of different diameters. The trimmers are exactly positioned by one or more arms W extending from the member W to engage one or more cooperating stops. As specifically illustrated, there are two arms W which alternately engage a single stop'lug V on the portion V of the member V. The arms have at their outer ends bearing faces W for enga ing opposite faces of the lug V when the member W is rotated on its pivot through an angle of 180. For smaller angular adjustment, exchangeable gauge blocks V are used, each of these corresponding to one-half the circular pitch of the particular gear being ground. After each trimming operation, the carrier frame V may be turned upward to withdraw thetrimming mechanism from interference with the grinder wheels.

To accurately set the grinder wheel D for grinding gear wheels having an odd number of teeth, I preferably proceed in the following manner: Both grinder wheels D and D arefirst trimmed to the same contour as previously described. I'he grinder wheel D is next operated to grind one tooth or interdental space of the gear wheel, the other grinder wheel D being withdrawn from contact with the work. The work holder is then indexed around to the position which is nearest to 180 from the position in which this first tooth was ground. The mounting for the grinder wheel D is then adjusted about the axis of the work holder to bring said wheel into exact registration with the ground tooth. The accuracy of this registration is easily determined by feeding the grinder wheel D into contact with the work and-observing whether. or 1 not'both sides of the grinder.

wheel; touch the. work simultaneously, this beingshown by .th'esparkslproduced on the contact. Ifone side of. the wheel touches the work before the other, further radvancement'of its mounting is required .to bring the wheel in. exact 'registra,-'

tion; There are, of course, other methods .of ac-' curatelyz-se'ttin'g the Wheel but' thistone, is easily nism for intermittently rotatively advancing the same to successive exactly predetermined posi tions in a cycle, of a plurality of similarly formed grinder wheels mounted in operative relation to the work in registration with spaced indexed positions thereof, a trimming mechanism, a. carrier for said trimming mechanism adapted to transfer the same into operative relation successively with each of said grinder Wheels, and means for exactly registering said trimming mechanism with the indexed position of said work holder in each of the grinding positions.

2. In a grinding machine, the combination with a rotary work holder and indexing mechanism for intermittently rotatively advancing the same to succesive exactly predetermined positions in a cycle, of a plurality of similarly formed grinder wheels mounted in operative relation to the work in registration with spaced indexed positions thereof, means for adjusting one of said grinder wheels in relation to the other to correspond to changes in indexing, a trimming mechanism, a carrier for said trimming mechanism adapted to transfer the same into operative relation successively with each of said grinder Wheels, and means for exactly registerme said trimming mechanism with the indexed position of said work holder in each grinding position, said registering means being adjustable to correspond with changes in indexing.

3. In a grinding machine, the combination with a rotary Work holder and intermittently operated indexing means therefor, of a plurality of similarly formed grinder wheels mounted in operative relation to the Work in registration with spaced indexedpositions thereof, separate feeding means for advancing each grinder Wheel during the performance of its work with a limited pressure permitting variations in the speed thereof in accordance with the resistance of the work, said feeder means alternating with theoperation of said indexing mechanism, and

.mean-s for synchronizing the feeding of said 1 grinder Wheels work with ,a limited pressure in the performance of their grinding operations, said motors permitting variations in the feeding speed of the respective grinder wheels in accordance with the resistance of the Work, and means for delaying the reversal of each hydraulic motor after the completion of its stroke in one direction until the other motor has completed its corresponding stroke thereby synchronizing said motors.

5. In a grinding machine, the combination;

with a. work holder, an indexing mechanism for intermittently advancing'the same to succwsive. exactly predetermined positions, of a. plurality of similarly formed grinder wheels mounted in operative relation to the work in registration with spaced indexed positions thereof,. a trim- 'ming mechanism having a pair of trimmers, for

fashioning opposite sides of said grinder wheels,

a carrier for said trimming mechanism adapted 10 to transfer the same into operahiverela'tion aucoessiveiy with each of said minder wheeismd; with the sepmfate trimmers thereof adapted to engage theycorresponding sides corsair! winder wheels, and means for exactly registering said; trimming mechanism. with the indexed position 0! said work holder in each 01' thegrindina positions. a V v FREDERICK A. e 

